How to Grow and Care for Blue Rug Juniper

Blue rug juniper is a drought-tolerant groundcover and hardy evergreen with silvery-blue foliage that takes on a purplish tone in winter. It prefers bright, sunny, well-drained slopes where water runs off quickly. It craves good soil drainage but tolerates most types of soil, temperatures, and humidity levels. This juniper is a practical solution for sunny slopes where water runs off quickly, and plants are apt to be thirsty.

Common Name	Blue rug juniper, creeping juniper, carpet juniper
Botanical Name	Juniperus horizontalis 'Wiltonii'
Family	Cupressaceae
Plant Type	Shrub, groundcover
Mature Size	3-6 in. tall, 6-8 ft. wide
Sun Exposure	Full
Soil Type	Well-drained
Soil pH	Acidic, neutral, alkaline
Hardiness Zones	3-9 (USDA)
Native Area	North America

Blue Rug Juniper Care

Blue rug juniper is a low-maintenance plant. Here are the main care requirements:

• Plant blue rug juniper only in full sun; it will not grow lush in too much shade.
• Choose cooler weather to plant blue rug juniper to give its roots time to acclimate.
• Space plants 4 to 6 feet apart so they can form a thick mat to crowd out weeds.
• Place this plant in any well-draining soil that does not retain water.
• Give this plant adequate airflow to prevent damp conditions.

Light

Blue rug junipers prefer to grow in full sun, meaning at least six to eight hours of direct sunlight on most days. These plants can tolerate shade and prefer protection from hot afternoon sun to prevent foliage burns. However, if in too much shade, the foliage will be sparse rather than lush.

Soil

Blue rug juniper is tolerant of various soil types, though it prefers to grow in dry, sandy soil with a pH range of 5.0 to 8.0. Excellent soil drainage is key to this plant's health.This shrub is also tolerant of rocky soil and salt from saltwater spray or road salt.

Water

Until a blue rug juniper plant matures, keep the soil evenly moist (but not soggy). After becoming established, it prefers moderate soil moisture and can tolerate some drought. However, soil that's too wet can kill the plant. So, only provide supplemental water to mature plants during extended dry spells or drought.

Temperature and Humidity

These plants can grow in a variety of temperatures and humidity levels. They can tolerate wide fluctuations of day-to-night temperatures, snow, and frost. They're best planted in the fall or early spring when temperatures are below 60 degrees Fahrenheit.

Planting in cooler weather establishes the root systems before hot and dry weather arrives. Moreover, humid or wet weather can cause stem dieback or root rot.

Fertilizer

Blue rug juniper grows well in average soil and tolerates somewhat poor soil. Although fertilizer isn't typically necessary, it is recommended that organic fertilizer be applied in the fall to boost mature plants, following the product label instructions.

Types of Creeping Juniper

Unlike the straight species Juniperus horizontalis, the cultivar 'Wiltonii,' does not produce dark blue berries, which take two years to mature.

Here are several other varieties of Juniperus horizontalis, commonly known as creeping juniper:

• 'Bar Harbor': This variety has blue-green foliage turning reddish purple in winter. It has a slow-to-medium growth rate.
• 'Blue Forest': A compact variety that spreads 1 to 5 feet in 10 years. Its foliage changes color from lavender in winter to blue in spring.
• 'Emerald Spreader': This variety has bright emerald green foliage throughout the year. Although low-growing, it spreads to 6 feet wide or more.
• 'Green Acres': As its name suggests, this variety grows lush dark green foliage.
• 'Monber' or 'Icee Blue': This variety, called by two names, features dense silvery-blue foliage that sometimes turns purple in the winter.

Pruning

Blue rug juniper grows moderately, reaching less than a foot tall, and can spread several feet wide, forming a dense mat. It doesn't require pruning unless its growth has become unruly or portions of the plant are damaged or diseased.

Trimming it can prevent the juniper from spreading outside its boundaries. Light pruning can also encourage robust growth and branching to create more fullness. Clean out any garden debris or trash lodged in this dense ground cover in the spring.

Trim the juniper in late winter or early spring when the weather is dry. Remove any dead or damaged portions, and cut back long branches to shape them, but by no more than a quarter of their length. Note that the center of the plant is considered a dead zone that does not see much sun, and pruning won't produce new growth, so gently remove the dead wood for better air circulation.

Propagating Blue Rug Juniper

Propagation from seed is not recommended for this cultivar. Blue rug juniper seeds produce a plant that is different from the parent plant. Though difficult and requires patience, propagation from stem cuttings may be possible. The best time to plant blue rug juniper is in the cooler temperatures of fall or early spring.

1. Take a 4- to 6-inch cutting with a sharp, disinfected knife from a healthy stem between late July and October (late summer to early fall).
2. Remove the needles from the bottom third of the cutting.
3. Dip the cut end in rooting hormone and bury it in a pot filled with moistened potting mix.
4. Place the cutting in bright, indirect light in a warm room, and keep the soil consistently moist. Root growth can take several months, sodon't transplant your cutting outdoors until next spring.

Common Pests and Plant Diseases

Blue rug juniper sometimes attracts aphids, bagworms, webworms, scale, and spider mites. To control the issue, insecticides or neem oil should be used.

Blue rug juniper is not bothered by serious disease problems. However, wet soil can lead to root rot, and in damp and rainy spring seasons, the plant is prone to fungal diseases and blights. Tip and twig blight causes younger needles to turn brown and drop off.

It can also be a host plant to cedar-apple and other rust diseases. Prune out infected parts of the plant and use fungicide to protect new growth in the future.

Blue rug juniper is also resistant to deer and air pollution.

Common Problems With Blue Rug Juniper

This is an easy-care plant but it can show signs of problems. Be on the lookout for these issues.

Center Dieback

As part of the natural aging process, the centers of mature blue rug juniper plants can show dieback and become unsightly. When tips and branches show dieback, it is usually a sign of blight.

Sprawling Bare Stems

A common complaint among gardeners is the lack of coverage this juniper offers on flat ground. This creeping juniper is best draped over retaining walls or slopes to exploit its sprawling stems. This plant requires full sun to grow lush.

Bare and dull-colored stems may also indicate a pest problem. Check for pests by holding a piece of plain white paper under a branch. Shake the branch to see if little specks fall onto the paper, then look under a magnifying glass to confirm if the dots are bugs infesting your blue rug juniper.

Scorched Stems

Creeping junipers are susceptible to the salts and acids in pet urine. Try to plant blue rug juniper in areas where pets do not wander, or the branches will appear burnt or scorched. If you think the plant is being sprayed with pet urine, rinse the plant with a garden hose.

From: thespruce